The present invention relates to sweat collectors for application to a body part of a subject in order to collect sweat therefrom for purposes of analysis. The invention also relates to methods of collecting and analyzing sweat in order to provide information useful in determining the medical condition of a subject.
The human body has two kinds of sweat glands, eccrine and apocrine sweat glands. Eccrine sweat glands secrete an aqueous solution of electrolytes (sodium chloride), urea, other metabolites and other organic compounds (e.g., lactic acid). These substances are secreted onto the skin, and are concentrated in certain body parts of the subject, particularly in the forehead and the palms of the hands, to effectively cool the skin of the subject by evaporative cooling. Apocrine sweat glands are located in hairy regions of the body, such as the armpits and around the groin, and secrete fatty materials and various organic substances, including pheromone hormones, thought to serve a biological function in sexual attraction.
The analysis of eccrine sweat for diagnosis of cystic fibrosis by measuring concentrations of the electrolytes (chloride, sodium, and potassium ions) has long been used in the clinics, as shown for example in U.S. Pat. No. 4,542,751. The analysis of apocrine sweat for diagnosis of various diseases by the use of patches has been proposed, e.g., U.S. Published Patent Application 2003/0199743. However, to date, the analytical results obtained for sweat analysis were not found sufficiently reliable and reproducible for any clinical application apart from cystic fibrosis.
Reference is also made to U.S. Pat. No. 5,050,604, in which the inventor of the present application is one of the joint inventors, disclosing an apparatus and method for monitoring the health condition of a subject in a continuous and non-invasive manner. The apparatus and method described in that patent includes a sweat collector unit and a sweat analyzing device both carried on the subject's body by a body attaching device. Also carried by the body attaching device is a container for a flushing solution that was continuously or periodically introduced into the sweat collector device so as to collect the sweat therein by flushing the skin. This patent also disclosed various health conditions detectable by analyzing the sweat, such as cystic fibrosis. It also disclosed various techniques for enhancing the production of sweat from the sweat glands, the collection of the sweat, and the analysis of the sweat to indicate the health condition of the subject. To simplify the description in the present application, the contents of U.S. Pat. No. 5,050,604 are incorporated herein by reference.
The collector and method described in U.S. Pat. No. 5,050,604 was designed for in situ analysis and not for quick and easy sampling for laboratory analysis.
Various analytical procedures are continuously being developed for analyzing substances in body liquids (namely blood and urine), to provide more accurate indications of the health condition of a person. However, because of the limitations of body-carried devices, such improved analytical procedures at the present time can be best performed in laboratories equipped with such analytical devices, rather than on the body of the subject whose health is being monitored.